1. Field of the Invention
This invention relates to a device for needling a prebonded web, comprising at least one needle board reciprocatingly movable in a stitching direction, a stitch base between a feed roller and a discharge roller. The stitch base is located directly opposite the needle board and forming a web guide that is convex in a direction of web movement.
2. Description of the Prior Art
In conventional needling devices the web is guided between the stitch base opposite the needle board and a stripper between the stitch base and the needle board, whose needles stitch into the web through through holes in the stripper. The stripper, which like the stitch base mostly consists of a perforated plate, has the function of retaining the web with respect to the needles emerging from the web, and of preventing the web from being entrained by the barbs of the needles. A conventional stripper between the stitch base and the needle board can, however, only be omitted when the web is urged against the web support against the withdrawal resistance of the needles. For this purpose, the stitch base may be provided with a curvature that is convex in direction of movement, and the web may be subjected to a corresponding tensile stress, which urges the web against the stitch base in cooperation with the convex support, so that the needles can be withdrawn from the web without having to risk that the web is lifted off the stitch base. The tensile stress acting on the web is easily achieved by means of a corresponding difference of the conveying speeds of the feed roller and the discharge roller. The omission of a stripper, which is possible as a result of these measures, makes possible an increased density of the needle distribution, because the needle distance is no longer restricted by the distance of the holes in the stripper, but only when this restriction is not imposed by the stitch base, which should therefore not be designed as a conventional perforated plate.